1. Technical Field
The invention relates to an electrochromic display device, and more particularly, to an electrochromic display device capable of multicolor display.
2. Related Art
Graetzel electrochromic display (ECD) is known as one of the potential techniques for electronic paper. The Graetzel ECD has advantages such as high contrast and rapid response. However, in conventional ECD, only one type of molecule is adsorbed to titanium oxide, and thus color change has been limited to one color associated with the color development and decoloring of the molecule.
As a method for colorization of ECD, for example, a method of using color filters, or a method of placing or laminating three color ECD devices together is suggested. However, these methods can cause deterioration of reflectivity and increase in cost.
Moreover, the type of usable dye molecules is limited because dye molecules used in ECD preferably have a plurality of carboxyl groups, phosphate groups or the like to serve as porous semiconductors having adequate bond strength to titanium oxide. This limitation is applicable not only to dye molecules, but to other various molecules to be adsorbed to a porous structure.